Definitions

1. adjective

relating to or affecting the atria of the heart, which are the upper chambers of the heart that receive blood from the veins and pump it into the ventricles.

“Atrial fibrillation is a type of irregular heartbeat.”

2. noun

the atria of the heart, which are the upper chambers of the heart that receive blood from the veins and pump it into the ventricles.

“The doctor examined the patient’s atria to diagnose the heart condition.”